Packaging machines are generally known in which a continuous web of material is converted into a plurality of individual pouches. The continuous web of material is folded in half over a plow to form two continuous side panels joined by a bottom fold. The folded web is passed through a series of seal bars which form transverse seals in between the side panels, thereby forming a strip of pouches interconnected by transverse seals. A cutter cuts through each transverse seal to form individual pouches with unsealed top edges. The individual pouches are transferred to a pouch filler, filled with product, and sealed. The sealed pouches are then collected for transport. Machines of this type may be categorized as either horizontal or vertical machines, depending on the general direction of web travel. The present invention relates to horizontal packaging machines in which the web travels horizontally.
The type and volume of product being packaged often determines whether the packaging process should use a continuously or intermittently advancing web. Certain products, such as hard candy, require a fill based on weight instead of volume. Scale fillers require relatively long periods to fill a pouch. As a result, slower cycle continuous motion or intermittent motion is required to provide additional fill time. In addition, larger volume fills require more time, and therefore intermittent motion through the filler may be necessary. More free flowing products, such as sugar, may be dispensed using a diving funnel suitable for filling continuously advancing pouches.
In light of the above, packaging machines have been developed specifically for either intermittent or continuous operation. In most conventional intermittent motion machines, the web is intermittently advanced between dwell periods, and operations are performed on the web during the dwells. In a continuous web motion machine, on the other hand, the web continually moves at a set rate and each station for performing operations is phased with the web to perform the operation as the web passes through the station.
The seal, cut, and other components of a packaging machine must be properly registered with the web, and with each other, to form pouches at the appropriate points along the continuous web. The web material is typically supplied with pre-printed artwork, such as brand names, designs, and other printed matter. As a result, not only must the components of the machine be properly spaced so that, for example, the vertical side sealers and the cutter perform at the same operative point, but the web must also be positioned in relation to the machine in general so that the operative point at which the components are performing aligns with the pre-printed artwork on the web.
Achieving registration in most conventional packaging machines, having either a continuously or intermittently advancing web, is overly difficult. Conventional packaging machines employ a number of components to perform various pouch forming, filling, and sealing operations. For example, the machines typically have one or more seal stations which contact the web to form side and bottom seals in the web. A cutter subsequently cuts the side seals to form individual pouches. The individual pouches are transferred to a device which carries the pouch through a pouch filler.
Registration is typically achieved one component at a time. Starting at the first seal station, for example, web material is fed through the machine and either the seal station or the web must be adjusted so that seals are formed at the desired points along the web. A similar procedure is used for the subsequent sealers, the cutter, and any other component requiring registration with the web. This conventional registration process requires a significant amount of time and labor, and wastes a significant amount of web material.
Related to the registration problem is the difficulty of adjusting conventional packaging machines to run different pouch sizes. As noted above, packaging machines employ a number of components for performing various pouch forming, filling, and seal operations. When pouch size is altered, each component must be repositioned or reconfigured to regain registration.
Some packaging machines, such as the continuous web advancing machine disclosed in U.S. Pat. No. 5,722,217 to Cloud, are overly burdensome to adjust and may only be adapted for a limited number of pouch sizes. The '217 device uses a sealing drum to form the vertical seals of the pouches. Sealing wires are circumferentially spaced about the sealing drum to provide sealing points. To adjust pouch width, the wiring configuration of the sealing wires must be changed. Even after making this adjustment, the sealing drum is capable of forming only a limited number of pouch widths which correspond with the spacing of the sealing wires. Another sealing drum having a different sealing wire arrangement must be used in order to form pouches having other pouch widths.
Other machines use components which are similarly difficult to adjust. U.S. Pat. No. 5,222,422 to Benner, Jr. et al., for example, discloses a machine using a cutter drum. A cone inside the drum is adjusted to change the radial position of the knives, thereby adjusting for different pouch widths. Once the cone is adjusted, the web must be run to verify that the knives cut at the desired pouch width. Readjustment and further testing may be required before the knives are properly positioned.
Adjustment of components in machines having an intermittently advancing web, while sometimes easier than in continuous web motion machines, is still overly cumbersome. The components of an intermittent web machine are positioned to contact the web at the appropriate location during a web dwell. It will be appreciated, therefore, that the components are typically spaced in increments equal to one or more pouch widths. A change in pouch width, therefore, requires repositioning of each component. Again, web material is run to determine whether the components are properly positioned, and readjustment may be necessary. Most conventional packaging machines are, accordingly, overly difficult to adjust for different pouch widths.
It will be appreciated that there are a number of different situations in which registration must be set. For example, registration adjustments are required when feeding a new web through the machine. In addition, the components must be adjusted when changing pouch sizes, or in the event of a web break. Accordingly, it is important for a packaging machine to quickly and easily achieve registration, while minimizing the amount of wasted web material.